| Andrew Cooke | Contents | Latest | RSS | Twitter | Previous | Next

C[omp]ute

Welcome to my blog, which was once a mailing list of the same name and is still generated by mail. Please reply via the "comment" links.

Always interested in offers/projects/new ideas. Eclectic experience in fields like: numerical computing; Python web; Java enterprise; functional languages; GPGPU; SQL databases; etc. Based in Santiago, Chile; telecommute worldwide. CV; email.

Personal Projects

Lepl parser for Python.

Colorless Green.

Photography around Santiago.

SVG experiment.

Professional Portfolio

Calibration of seismometers.

Data access via web services.

Cache rewrite.

Extending OpenSSH.

Last 100 entries

The Black Dork Lives!; The UN Requires Unaninmous Decisions; LPIR - Steganography in Practice; How I Am 6; Clear Explanation of Verizon / Level 3 / Netflix; Teenage Girls; Formalising NSA Attacks; Switching Brakes (Tektro Hydraulic); Naim NAP 100 (Power Amp); AKG 550 First Impressions; Facebook manipulates emotions (no really); Map Reduce "No Longer Used" At Google; Removing RAID metadata; New Bike (Good Bike Shop, Santiago Chile); Removing APE Tags in Linux; Compiling Python 3.0 With GCC 4.8; Maven is Amazing; Generating Docs from a GitHub Wiki; Modular Shelves; Bash Best Practices; Good Emergency Gasfiter (Santiago, Chile); Readings in Recent Architecture; Roger Casement; Integrated Information Theory (Or Not); Possibly undefined macro AC_ENABLE_SHARED; Update on Charges; Sunburst Visualisation; Spectral Embeddings (Distances -> Coordinates); Introduction to Causality; Filtering To Help Colour-Blindness; ASUS 1015E-DS02 Too; Ready Player One; Writing Clear, Fast Julia Code; List of LatAm Novels; Running (for women); Building a Jenkins Plugin and a Jar (for Command Line use); Headphone Test Recordings; Causal Consistency; The Quest for Randomness; Chat Wars; Real-life Financial Co Without ACID Database...; Flexible Muscle-Based Locomotion for Bipedal Creatures; SQL Performance Explained; The Little Manual of API Design; Multiple Word Sizes; CRC - Next Steps; FizzBuzz; Update on CRCs; Decent Links / Discussion Community; Automated Reasoning About LLVM Optimizations and Undefined Behavior; A Painless Guide To CRC Error Detection Algorithms; Tests in Julia; Dave Eggers: what's so funny about peace, love and Starship?; Cello - High Level C Programming; autoreconf needs tar; Will Self Goes To Heathrow; Top 5 BioInformatics Papers; Vasovagal Response; Good Food in Vina; Chilean Drug Criminals Use Subsitution Cipher; Adrenaline; Stiglitz on the Impact of Technology; Why Not; How I Am 5; Lenovo X240 OpenSuse 13.1; NSA and GCHQ - Psychological Trolls; Finite Fields in Julia (Defining Your Own Number Type); Julian Assange; Starting Qemu on OpenSuse; Noisy GAs/TMs; Venezuela; Reinstalling GRUB with EFI; Instructions For Disabling KDE Indexing; Evolving Speakers; Changing Salt Size in Simple Crypt 3.0.0; Logarithmic Map (Moved); More Info; Words Found in Voynich Manuscript; An Inventory Of 3D Space-Filling Curves; Foxes Using Magnetic Fields To Hunt; 5 Rounds RC5 No Rotation; JP Morgan and Madoff; Ori - Secure, Distributed File System; Physical Unclonable Functions (PUFs); Prejudice on Reddit; Recursion OK; Optimizing Julia Code; Cash Handouts in Brazil; Couple Nice Music Videos; It Also Works!; Adaptive Plaintext; It Works!; RC5 Without Rotation (2); 8 Years...; Attack Against Encrypted Linux Disks; Pushing Back On NSA At IETF; Summary of Experimental Ethics; Very Good Talk On Security, Snowden; Locusts are Grasshoppers!; Vagrant (OpenSuse and IDEs); Interesting Take On Mandela's Context

© 2006-2013 Andrew Cooke (site) / post authors (content).

Quanterra Q330 Calibration - Control Conventions

From: andrew cooke <andrew@...>

Date: Thu, 30 Jun 2011 19:38:39 -0400

This is work-related; I'm posting it to my personal blog just to make it
available to others.  Credit to Joel Edwards at USGS Albuquerque (who
explained most of this to me) and ISTI (my employers).


The Q330 has 8 output (control) lines that can be connected to local hardware
(nominally 4 lines per sensor).  These use 0/5V levels and are controlled
directly by the "Sensor Control Bitmap".

An invocation of the C1_QCAL command can set these lines "however it pleases".
For example, if the "Sensor Control Bitmap" is set to 0x1 then the first line
is set to 5V and all others are set to 0V.


So far, so simple.

However, the Q330 documentation and firmware also support a set of conventions
that allow the meaning of these lines to be stored and read, and so allow the
control software to make "intelligent" decisions about how to set the lines
for particular commands.

These conventions are as follows:

  - A set of names for the 8 lines.  These are displayed in the Willard
    software, named as:

      Sensor A:
	GENEN 1-A, GENEN 2-A, GENEN 3-A, CALEN-A

      Sensor B:
	GENEN 1-B, GENEN 2-B, GENEN 3-B, CALEN-B

  - A set of "labels" that identify uses for the lines:

      Not doing calibration or re-centring 
      Sensor A calibration 
      Sensor A centring 
      Sensor A capacitive coupling 
      Sensor B calibration 
      Sensor B centring 
      Sensor B capacitive coupling 
      Sensor A Lock 
      Sensor A Unlock 
      Sensor A Aux1 
      Sensor A Aux2 
      Sensor B Lock 
      Sensor B Unlock 
      Sensor B Aux1 
      Sensor B Aux2 

The firmware allows each name to be associated with (1) a label and (2) a flag
for active high.  This is written to the Q330 via the C1_SSC command and read
via C1_SC.

So, for example, the user might decide that Lines GENEN 1-A and CALEN-A are
both labelled "Sensor A calibration", and that the first of these is "active
high" while the second is "active low".


Given the above we can now describe how control software uses the conventions
to make "intelligent decisions".  For example, when running calibration the
software "knows" that it must trigger calibration for sensor A.  Consulting
the table of information described above it can infer that it must set GENEN
1-A (bit 0) to 1 (active high) and CALEN-A (bit 3) to 0 (active low).  The
other bits would need to be set to their "inactive" states (assuming they were
set to labels that had nothing to do with calibration).


In summary:

 - The Q330 itself does not apply any logic itself.  It simply sets the line
   voltages according to the bitmap supplied.
 - A set of conventions allow the physical configuration (wiring) to be
   described and saved on the Q330.
 - Control software can read this information and, following the conventions,
   control the output lines correctly.


Finally, the "error" in qscal comes from no line being labelled with
"capacitive coupling".  The software checks for this when a capacitively
coupled calibration is made.  This is a "logical" check (if the operator has
not recorded any wire to be used to enable capacitive coupling then it probably
does not make sense to ask for such a thing) inferred from the conventions
above.  It does not reflect any actual error in the low level behaviour of the
system.

Comment on this post